A Pd(II)-catalyzed reaction engaging alkenyl β-keto esters is reported that leads to the formation of 1-naphthols and an unexpected generation of arylpalladium(II) species. Interception of the in situ generated arylpalladium(II) species in a Mizoroki-Heck reaction, together with additional mechanistic studies, provided strong evidence in support of the first aromatization-driven β-carbon elimination process. A single Pd catalyst served to promote a series of both C-C bond forming and cleavage events in an unprecedented manner.

Au(I)-catalyzed cyclization of alkenyl carbonyl compounds leading to a variety of substituted naphthalenes has been developed. This process exploits a dual function of the Au(I) catalyst: (1) the oxophilic nature of the Au(I) catalyst, counterintuitive to the π-acidic reactivities generally associated with Au catalysts, and (2) olefin isomerization supported by the outcome of isotope scrambling experiments. It cannot be completely excluded that TfOH is a true operative catalyst in this protocol. In view of the practicality, the unnecessity of isomerically pure starting material in this reaction is particularly attractive and valuable.

Two new coumarin derivatives displayed highly selective "Off-On" fluorescence changes with pyrophosphate between various anions including ATP, ADP, AMP and inorganic phosphate in 100% aqueous solution.

No abstract

A AuI -catalyzed intramolecular cyclization reaction of 2-alkenylphenyl carbonyl compounds to afford a variety of indene, indenol, and indanone ring systems was developed. In this process, Au I serves to activate the carbonyl group of β- IntroductionTransition-metal-catalyzed carbon-carbon bond formation reactions between 1,3-dicarbonyl compounds and alkenes have been of significant synthetic interest in recent years. [1] In general, such transformations operate through the nucleophilic character of the 1,3-dicarbonyl functionality, forging a carbon-carbon bond with the alkene component through π-philic transition-metal activations (Scheme 1, path a). Au III and Au I are both well documented soft π-philic Lewis acids that show a high degree of electrophilicity towards carbon-carbon multiple bonds, generating an activated species that is susceptible towards nucleophilic Scheme 1. Transition-metal-catalyzed reactions between β-keto carbonyl compounds and olefins.[ attack. [1c-1e,2] Meanwhile, it has also been reported that Au III can exhibit oxophilic character towards the carbonyl group, thereby rendering an electrophilic nature to the latter functionality. [3][4][5] In stark contrast, synthetic applications that exploits the oxophilicity of Au I remains scarce, especially in substrates bearing C=C bonds where the latter functionality is known to be more susceptible towards activation by Au I catalysts.[6] As a pioneering example, Liu and co-workers reported a Au I -catalyzed deoxygenative Nazarov cyclization of 2,4-dien-1-als in the preparation of cyclopentene derivatives, demonstrating the oxophilicity exhibited by Au I catalysts towards the aldehyde functionality.[6b,6c] Herein, we report an unprecedented Au I -catalyzed intramolecular cyclization reaction of 2-alkenylphenyl carbonyl compounds (Scheme 1, path b). In particular, for the first time, oxophilic activation of alkenyl β-keto esters has been demonstrated, thereby rendering the latter functionality susceptible to nucleophilic attack by the pendent Exploring the Oxophilic Lewis Acidity of Au I Specie alkenyl moiety. This protocol enabled convenient entry to a variety of indenes, [7] indenols, [8] and indanones, [9] which are privileged structural motifs found in a diverse array of compounds possessing important physical and biological properties.[10] Results and DiscussionPrompted by recent reports of Au-catalyzed addition of 1,3-dicarbonyl compounds to alkenes, [1c-1e,2] we initially anticipated a Au-catalyzed intramolecular cyclization of alkenyl β-keto esters 1a to afford tetralone A and/or its oxidatively aromatized derivative naphthol B (Table 1).[11] Much to our surprise, treatment of 1a with Ph 3 PAuCl/AgOTf (1:1, 5 mol-%) in ClCH 2 CH 2 Cl (0.025 m) at 100°C led to, exclusively, the formation of indene 2a in 70 % yield (Table 1, Entry 1). We speculated this unexpected outcome originates from initial nucleophilic attack at the ketone moiety by the stilbene olefin, followed by subsequent dehydration. Expected products A and B, or C, [1h,1i] re...